Japanese encephalitis

definition

Japanese encephalitis is a tropical disease that occurs mainly in East and Southeast Asia. It is caused by the Japanese encephalitis virus, which is transmitted to humans through a mosquito bite.

In most cases, an infection proceeds without serious symptoms. However, in severe cases, inflammation of the brain (Encephalitis) develop with impaired consciousness, paralysis and epileptic seizures.

A causal therapy is not available. A vaccination against the disease is possible.

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Causes of Japanese Encephalitis

Japanese encephalitis is a tropical disease caused by viruses. The Japanese encephalitis virus belongs to the same group as the virus that causes yellow fever. A person can become infected with it through a mosquito bite.

The disease is a Zoonosis. These are diseases that can be transmitted from vertebrates to humans.

The mosquito acts as a disease carrier. Intermediate hosts for infection in humans are mostly domestic animals such as pigs or horses. The disease is widespread in Asia. The risk of infection is particularly high in rural areas; at the end of the rainy season.

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Diagnosis of Japanese encephalitis

Japanese encephalitis presents itself clinically with the typical symptoms of encephalitis: impaired consciousness, paralysis and epileptic seizures.

The blood test shows an increase in white blood cells (Leukocytosis). Antibodies against the virus can sometimes also be detected. You can also use nerve water (Liquor) examine; here you can see more inflammatory cells with normal sugar concentration.

This is a typical finding of virus-related inflammation. A special test method (PCR) can also be used to detect the virus directly in the nerve water.

Accompanying symptoms of Japanese encephalitis

Most patients experience no or only discrete symptoms such as tiredness, headache and a slight fever; most likely comparable to a flu-like infection.

However, in severe cases, inflammation of the brain (Encephalitis) develop. Characteristic for this stage are sudden onset of high fever, chills, and headache and body aches.

Neurological symptoms appear a short time later. These are mostly severe disturbances of consciousness up to a coma. Paralysis, speech disorders or epileptic seizures can also occur.

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Japanese encephalitis therapy

Japanese encephalitis is caused by a virus. Unfortunately, there is currently no drug that can be used to treat the cause of the disease. Only purely symptomatic therapy is possible, i.e. the corresponding symptom is treated. The course of the disease can hardly be influenced by this.

In most cases, pain relievers or anti-inflammatory drugs such as ibuprofen are sufficient to improve the general condition.

If it comes to encephalitis (Encephalitis) with impaired consciousness, the patient must be treated in an intensive care unit. Artificial respiration is then usually necessary.

Vaccination against Japanese encephalitis

Since 2009 there has been a new well-tolerated inactivated vaccine against the Japanese encephalitis virus. It is commercially available under the name Ixiaro ®. Children from 2 months old can be vaccinated with it.

The vaccination is not one of the standard vaccinations recommended in Germany. It is recommended for longer or repeated trips to rural areas of South-East Asia. Especially in the vicinity of rice fields, at the end of the rainy season, the risk of infection is high. Adults receive 2 doses, on days 0 and 28. Vaccination protection exists 7 days after the second dose for about 10 years.

Read more on the topic: Vaccination against Japanese encephalitis

Duration of Japanese encephalitis

Symptoms may appear after an incubation period of 5-15 days. In most cases the disease has relatively few symptoms. Some patients complain of a slight headache and fever, similar to a flu-like infection.

This is over after one week on average. In severe cases, however, encephalitic symptoms occur suddenly after a few days without symptoms. The patient's condition worsens dramatically with a very high fever, impaired consciousness, paralysis.

Intensive medical treatment is necessary during this time. If the disease is survived, it takes weeks to months for the patient to recover from it. Consequential damage often persists.

Forecast of Japanese encephalitis

The prognosis depends on the course of the disease. Most healthy adults have fewer symptoms. Older people and children are at higher risk of the encephalitic course (with encephalitis).

Here the prognosis is rather bad. Up to 30% die of encephalitis. Recovery usually takes months; neurological sequelae remain.

Consequential damage in Japanese encephalitis

If the infection with the Japanese encephalitis virus causes inflammation of the brain, the prognosis is poor. About 30% of those affected die from the disease. The others often suffer from consequential damage.

In addition, it often takes weeks to months for the patient to recover from the disease. Numerous consequential damages are described. This ranges from cognitive deficits (reduced memory, difficulty concentrating) to movement disorders. This can be paralysis or imbalance.

Sometimes the patients also have problems speaking or swallowing; a speech therapy follow-up treatment is important here.